1. Field of the Invention
The invention relates to a device for removing printed products transported uniformly spaced and astraddle on a transport device, wherein the device comprises a rotatingly driven gripping device with controlled gripping elements which grip a printed product on the transport device in the area of folding and remove it while maintaining it in a stable position.
2. Description of the Related Art
A device of the aforementioned kind is known in the prior art, for example, in EP 0 771 675 A1, assigned to the instant assignee. This device has a clamping device which describes a circular travel path and picks up a single printed product while being transported and removes it in a position-stable fashion from a conveying chain and supplies it to a further processing device. This device is used, in particular, for gather-stitcher devices and has been proven successful in practice. Such devices are also referred to as deliveries. A further device of this kind is known from U.S. Pat. No. 4,482,141.
In the known device it is important that the printed products while being transported are safely gripped by the grippers and are removed from the transport device in a position-stable way. The printed products to be removed can be of very different thickness.
Printed products are known which are comprised only of a thin sheet and which are very lightweight and unstable. On the other hand, very thick, and correspondingly heavy, printed products must be processed. For a high transport output, in particular, in the case of very thin as well as very thick products disruptions can occur which can be avoided only with very complicated adjusting processes.
It is an object of the invention to provide a device of the aforementioned kind such that printed products having very different thicknesses can be processed safer, faster and with less adjusting work.
In accordance with the present invention, this is achieved in that the control means, which are provided for the closing movement and/or opening movement of the gripping means, are adjustable during operation for adaptation to the thickness of the printed products.
According to the invention, control means are provided for the movement of the gripping means which control means, for adjustment to the thickness of the printed products, can be readjusted during operation or running. By adjusting the control means it is possible to adjust the clamping force of the gripping means precisely to the thickness of the printed product being transported. Preferably, for this purpose the thickness of the printed product is measured by means of a measuring device. Based on the measured thickness, the closing movement of the gripping means is controlled such that the printed products are gripped with optimal clamping force. Since the movement can be readjusted during operation, a readjustment is thus possible, even at high conveying output, so that printed products of very different thicknesses can be successively processed without any interruption. For each gripping cycle, the closing movement can be adjusted by readjusting precisely to the thickness of the printed product. For example, printed products of a thickness of, for example, 1 mm, and, subsequently, one of a thickness of 20 mm, can be gripped with an optimal clamping force, respectively.
It was found that the control means can be adjusted very quickly with mechanical means, for example, within 100 milliseconds.
According to a further embodiment of the invention, two grippers are controlled by means of a lever which has a roller that is pressed against a control curve of a curve ring. By means of a control disc, this curve ring is moved during operation horizontally such that the position of the aforementioned control curve is changed. The movement of this curve ring is carried out preferably by means of a further control disc which also has a control curve and is adjustable during operation on curve levers fixedly mounted on the frame.
The adjustment is carried out according to a further embodiment of the invention preferably by means of two curve levers which, for example, are pivotable by means of a pneumatic drive. Such a pivoting action can be very quickly and very precisely performed based on a signal which corresponds, for example, to a thickness measurement carried out by means of a sensor. In principle, the readjustment causes a radial rotational movement of a control disc to be transformed into an axial movement of a curve ring.